1. Field of the Invention
The present invention relates to a polyphenylene ether resin composition having an excellent impact resistance.
2. Description of the Related Art
A polyphenylene ether is known as a thermoplastic resin having an excellent heat resistance, mechanical performances and electric characteristics, but has a poor processability and impact resistance and improvement of these properties is desired. For example, as the means for improving the processability of the polyphenylene ether resin, U.S. Pat. No. 3,383,435 has proposed a resin composition comprising a polyphenylene ether resin and a polystyrene resin or rubber-modified polystyrene resin. This resin composition, however, does not have a satisfactory impact resistance. Techniques of specifying particle sizes of a rubbery elastomer phase dispersed in the resin composition for improving this poor impact resistance have been proposed. For example, Japanese Examined Patent Publication No. 51-28659 teaches that, if the size of particles of the dispersed rubbery elastomer phase is in the range of from 0.5 to 2 .mu.m, an improved impact resistance is manifested. Furthermore, for example, in the Encyclopedia of Polymer Science and Technology, Volume 13, page 392, 1970, it is taught that a polystyrene resin gives a molded article having a satisfactory impact resistance if the size of particles of a rubbery elastomer dispersed in the polystyrene resin is in the range of from 2 to 5 .mu.m. In the case of a polyphenylene ether resin, however, even if the average particle size of the dispersed rubbery elastomer is adjusted to 0.5 to 2 .mu.m, the impact resistance is only slightly improved, and a satisfactory molded article cannot be obtained. If the average particle size of the rubbery elastomer phase is greater than 2 .mu.m, the impact resistance is reduced and the molded article cannot be practically used.